Background: Intracranial pressure (ICP) monitoring in traumatic brain injury (TBI) is common. Yet, its efficacy varies between studies, and the actual effect on the outcome is debated. This study investigates the association of ICP monitoring and clinical outcome in patients with an isolated severe blunt TBI. Patients and Methods: Patients were recruited from the American College of Surgeons-Trauma Quality Improvement Program database during 2014. Inclusion criteria were limited to adult patients (≥18 years) who had a sustained isolated severe intracranial injury (Abbreviated Injury Scale [AIS] head of ≥3 and Glasgow Coma Scale [GCS] of ≤8) following blunt trauma to the head. Patients with AIS score >0 for any extracranial body area were excluded. Patients' demographics, injury characteristics, interventions, and outcomes were collected for analysis. Patients receiving ICP monitoring were matched in a 1:1 ratio with controls who were not ICP monitored using propensity score matching. Results: A total of 3289 patients met inclusion criteria. Of these, 601 (18.3%) were ICP monitored. After propensity score matching, 557 pairs were available for analysis with a mean age of 44 (standard deviation 18) years and 80.2% of them were male. Median GCS on admission was 4[3,7], and a third of patients required neurosurgical intervention. There were no statistical differences in any variables included in the analysis between the ICP-monitored group and their matched counterparts. ICP-monitored patients required significantly longer intensive care unit and hospital length of stay and had an increased mortality risk with odds ratio of 1.6 (95% confidence interval: 1.1–2.5, P = 0.038). Conclusion: ICP monitoring is associated with increased in-hospital mortality in patients with an isolated severe TBI. Further investigation into which patients may benefit from this intervention is required.